1. Field of the Invention
The present invention relates to a magnetic read head and magnetic read write system equipped with a magnetoresistive element.
2. Background Art
In the market of magnetic read write systems, the improvement of recording density exceeding the annual rate of 40% has been required, and also in corresponding magnetic read write heads, the improvement of performance for both read and write functions has been required. Among these, it is important for magnetic read heads to satisfy three technical problems: the improvement of sensitivity elevating technology, the improvement of track width reducing technology, and the improvement of read gap distance reducing technology.
In recent years, studies and device development related to the exchange effect between spin-polarized current and magnetization have been actively carried out. For example, as described in “Electrical Detection of Spin Procession in a Metallic Mesoscopic Spin Valve”, F. J. Jedema et al., NATURE, Vol. 416, pp 713-716, 18 April 2002, it has been confirmed that a spin current having a polarized spin polarizability in conducted for a distance as long as 100 nm or more to cause a magnetic exchange effect. They prepared thin Co wires having different thicknesses and thin Al wires orthogonal thereto, and fabricated a structure wherein an alumina barrier layer was formed on the location where a thin Co wire intersects with a thin Al wire. At this time, when a current was flowed from a thick Co wire to an Al wire and a magnetic field was supplied to the film, a potential difference depending of the magnetic field occurred between the Co wires and Al wires wherein no current was flowed, and even if the distance between these thin wires exceeded 500 nm, a magnetic exchange effect was observed. This has been theoretically recognized as described in, for example, Physical Review B, Vol. 59, No. 1, pp 93-97 and Physical Review B, Vol. 65 054401, pp 1-17, as the effect when spin polarized electrons are accumulated in the boundary portion of the thin Al wire, and occurs when the accumulated spin polarized electrons are distributed into a wide region in the thin wires.
In general, such elements are characterized in that if there are two magnetic bodies having different coercivity from an external magnetic field, change in potential of a magnetic body to the conductor is created as an output; and the potential is characterized in that the potential has different polarity depending on whether the magnetization of the two magnetic bodies are parallel or antiparallel. In the above-described structure, the magnetic body consists of simple Co, which is connected to Al. Even in this structure, output with changing in magnetic field can be obtained at normal temperature.
[Non-Patent Document 1]NATURE, Vol. 416, pp 713-716,18 Apr. 2002[Non-Patent Document 2]Physical Review B, Vol. 59, No. 1, pp 93-96[Non-Patent Document 3]Physical Review B, Vol. 65 054401, pp 1-17